U.S. patent application number 10/458305 was filed with the patent office on 2004-02-19 for method and apparatus to authenticate digitally recorded information.
This patent application is currently assigned to Accurate Automation Corporation of Chattanooga, Te. Invention is credited to Cox, Chadwick James, Gibson, Zachariah Morgan, Hayton, Stephen Ralph, Pap, Robert Michael, Wood, Thomas Paine.
Application Number | 20040034779 10/458305 |
Document ID | / |
Family ID | 31720483 |
Filed Date | 2004-02-19 |
United States Patent
Application |
20040034779 |
Kind Code |
A1 |
Wood, Thomas Paine ; et
al. |
February 19, 2004 |
Method and apparatus to authenticate digitally recorded
information
Abstract
A method and apparatus to verify the authenticity of the
recording is provided. An authentication code is calculated based
on the contents of the recording and information describing the
context of the recording. The authentication code provides
assurance to a user of the recording that no elements of the
recording have been altered. Recordings that are made for legal
evidence purposes may include, but are not limited to audio and
visual (image) information including motion pictures. Context
information includes, but is not limited to date, time, longitude,
latitude, camera or recorder serial number, camera orientation,
camera optical parameters, and information about the recorder
operator. When using such recordings for legal evidence, the
authenticity of the recorded information is crucial, and also the
authenticity of the parameters surrounding the recording is
crucial. The method and apparatus contained herein permits
unrestricted use of the recorded information, and provides a test
of authenticity of the entire recording. Additionally, the serial
number of the recorder is authenticated.
Inventors: |
Wood, Thomas Paine; (Signal
Mountain, TN) ; Cox, Chadwick James; (Chattanooga,
TN) ; Gibson, Zachariah Morgan; (Chattanooga, TN)
; Hayton, Stephen Ralph; (Kettering, OH) ; Pap,
Robert Michael; (Chattanooga, TN) |
Correspondence
Address: |
Janet C. Donovan
7001 Shallowford Road
Chattanooga
TN
37421
US
|
Assignee: |
Accurate Automation Corporation of
Chattanooga, Te
Chattanooga
TN
|
Family ID: |
31720483 |
Appl. No.: |
10/458305 |
Filed: |
June 11, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60387923 |
Jun 13, 2002 |
|
|
|
Current U.S.
Class: |
713/176 ;
380/277; 705/56 |
Current CPC
Class: |
H04L 2209/608 20130101;
H04L 2209/805 20130101; H04L 9/3247 20130101 |
Class at
Publication: |
713/176 ; 705/56;
380/277 |
International
Class: |
H04L 009/00 |
Claims
We claim:
1) A method and apparatus to authenticate a digital recording
comprising: a) a means to create the digital recording, b) a means
to process the digitally recorded elements of the scene to prepare
for digital recording, c) a means to digitally store the recorded
information in digital memory media, d) a means to supplement the
digitally recorded information with parameters indicating the
conditions under which the recording was made (including, but not
limited to, date, time of day, location, camera or recorder number,
operator name, etc.), e) a means to compute a digital signature of
the combination of the recorded information and the associated
information, f) a means to encrypt or hide the digital signature in
a similar quantity of data that cannot be produced without
knowledge of the digital signature process and knowledge of the
hiding process, g) a means to restore the original digital
signature from the encrypted digital signature, h) and a means to
compare the calculated digital signature with the digital signature
that was stored, and to declare the file or record authentic if the
digital signature is unchanged from the original recording, and to
declare the file or record non-authentic if the digital signature
is altered from the original recording.
2) The method and apparatus of claim 1 wherein: a) the visual
sensor, if present, is a camera generating a signal corresponding
to the visual content of the scene, b) the audible sensor, if
present, is a microphone generating a signal corresponding to the
audio content of the scene c) the location sensor, if present, may
be a GPS (Global Positioning System) device determining longitude
and latitude d) the temperature sensor, if present, is a thermal
sensor generating a signal corresponding to the temperature of the
scene, e) other electronic environmental sensors may be present to
include those measurements in the recording.
3) The method and apparatus of claim 1 wherein the digital
signature process may be: a) a checksum process, b) or any
arithmetic process based on all of the recorded data and all of the
parameters associated with the recorded data, c) or any arithmetic
process based on a defined subset of the recorded data and a
defined subset of the parameters associated with the recorded
data.
4) The method and apparatus of claim 1 wherein the encryption
process is: a) a public key encryption process, b) or a symmetric
key encryption process, c) or any secret encryption process.
5) The method and apparatus of claim 1 wherein the authentication
encode process is: a) integrated closely with the recording
mechanism (tightly coupled), b) or performed much later by a
different computing mechanism (loosely coupled).
Description
CITED REFERENCES
U.S. Patent Documents
[0001] U.S. Pat. No. 6,269,446 July 2001 Schumacher, et al.
[0002] U.S. Pat. No. 6,185,316 February 2001 Buffam
[0003] U.S. Pat. No. 5,987,136 November 1999 Schipper, et al.
[0004] U.S. Pat. No. 5,499,294 March 1996 Friedman
BACKGROUND OF THE INVENTION
[0005] Digital recorders such as image (video) and sound recorders
have become very widely used because of the ease of transporting a
recording between users. It is practical to transport a digital
recording across a local area network or across the internet.
Additionally, it is practical to present a digital recording to
multiple users simultaneously. Unfortunately, it has become very
easy to alter digital recordings with inexpensive computers and
software tools.
[0006] When a digital recording is offered as evidence that an
incident occurred, one must question the authenticity of the
recording. One technique to detect alterations of a digital image
is a digital "watermark." This embeds a digital authentication code
directly into the recorded picture, presumably in a manner that
does not affect the perceived quality of the picture. However, a
digital "watermark" is an alteration, and in some situations any
alteration is perceived negatively.
[0007] Some recording situations exist solely for the purpose of
providing evidence, such as surveillance situations. In these
situations, it is desirable to authenticate not only the recorded
picture and the recorded sound, but it is additionally desirable to
authenticate other recorded information such as time, place,
recorder settings, recorder serial number, camera parameters,
perhaps the operator of the recorder, and other parameters. Without
authentication it is possible to falsify a recording by altering
the related parameters while leaving the picture or sound original.
A picture or sound recorded at one point in time, but altered to
represent a recording at a different point in time may cause the
user of that recording to reach an incorrect conclusion.
[0008] It is common practice to consolidate recorded information
and recording parameters in a digital "file" or "record." Many
industry standards exist for such consolidated information such as
JPEG (Joint Photographic Experts Group) and TIFF (Tagged Image File
Format) in the picture industry, as well as MPEG (Motion Pictures
Expert Group) in the audio/visual multimedia industry. Standard
file formats must include information to completely rebuild the
recording. Such information includes, at a minimum, the number of
bits per pixel, whether a picture is monochrome or color, the
number of horizontal pixels and the number of vertical pixels, the
compression style (if any), scan directions (left to right, top to
bottom), and other image parameters. Sound recordings must include
sample rates, bits per sample, and compression styles (if any.)
Many industry standards include provision for many digital
parameters to be consolidated with the digitized pictures and
sound. Collectively, all of the information recorded in a file or
record is used to represent the recording and its attributes.
[0009] Information can be included in a file or record that
represents a recording to indicate the conditions of the recording.
This supplementary information can include date, time of day,
location, camera or recorder number, operator, and other relevant
information. A digital file or record may include a recording or
recordings and information about the conditions of the recording.
This file or record may be transported from the memory or disk of
the recording computer to the memory or disk of other computers in
the process of routine processing. Eventually, when the file or
record of the recording is presented to an observer, it is
desirable to include a means to verify that the observed recording
and associated parameters are the same as the recording and
parameters at the moment of recording. This verification of
authenticity must be applied to the entire recording and associated
information for the observer to fully trust that the digital file
or record which is observed is identical to the recording and
associated information at the moment of the original recording.
[0010] The unique function offered by this invention is the ability
to authenticate both a recording and the conditions under which the
recording was made. This authentication is later used when the
recording is reviewed to confirm that what is reviewed is unaltered
from the original recording. Means have existed to authenticate a
picture, which would permit detection of any alteration of the
picture from the original recording. But, those authentication
means would permit an alteration or misrepresentation of the
conditions of the recording to go undetected. A picture that was
actually recorded at one instant of time could be represented as
having been recorded at a different instant of time. Sometimes,
recording conditions such as time of day are superimposed on the
picture. This is undesirable because the characters representing
the time may interfere with objects of interest within the picture.
Additionally, it would be impractical to superimpose several
conditions of recording including, but not limited to, date, time
of day, longitude, latitude, recorder number, camera parameters,
operator name, and other information onto the picture without
significant loss of information content of the picture.
SUMMARY OF THE INVENTION
[0011] The invention claimed herein is an apparatus and process to
authenticate a digital recording and the conditions under which the
recording was made. The authentication process claimed in this
invention adds an authentication record to a digital recording in a
way that does not affect the recording and does not affect the
review of the recording. The authentication process claimed in this
invention can be exercised when the recording is reviewed to
determine if the recording and its related conditions are unchanged
from the original recording.
[0012] For the purpose of this invention, the following definitions
shall apply:
[0013] Digital Recording--any information pertaining to a scene
that is recorded with a digital sensor onto digital media. A
digital recording may include, but is not limited to, recordings of
sound, pictures, temperature, location, and time.
[0014] Authentication--the ability of a person reviewing a digital
recording to determine with confidence: a) the context in which the
recording was made, and b) that the recording they are reviewing is
unchanged from the original recording.
[0015] Conditions of Recording--the conditions at the instant the
digital recording is produced. Conditions may include, but are not
limited to, date, time of day, longitude, latitude, temperature,
the serial number of the recorder, sensor parameters, and
information about the person operating the recorder.
[0016] Original Digital Recording--a digital recording together
with the conditions of recording that is unchanged from the instant
the recording was made.
[0017] Tightly Coupled Authentication--a situation where the
authentication encode process is an integral element of the digital
recording process. This includes embedding the authentication
encode devices directly into the digital recorder.
[0018] Loosely Coupled Authentication--a situation where the
authentication encode process is not an integral element of the
digital recording process, but rather is performed significantly
later than the recording process by a different computing
mechanism. This is the case where it is not practical to integrate
authentication encode into the recording mechanism.
[0019] The authentication process claimed herein consists of an
encoding process and a decoding process. In the authentication
encoding process, an authentication record is computed at the
instant the recording is made, and the authentication record is
appended to the original digital recording. The authentication
record has no effect on the process of reviewing the digital
recording. Any device which is capable of reviewing a digital
recording that does not contain an authentication record can also
review the same digital recording containing an authentication
record. The authentication record is a passive attachment. The
authentication encoder may be a hardware device which is integrated
with the digital recorder or the authentication encoder may be a
software process that is executed within the processor that
prepares the sensed information for recording. Each authentication
encoder has a unique digital serial number which is contained
within the authentication encoder device or processor. The
authentication encoder must be carefully prevented from
unauthorized copying to prevent fraudulent authentication encoding.
If an unauthorized authentication encoder was made, it would be
possible to produce a digital recording that had been properly
authentication encoded, remove the authentication record, modify
the digital recording and/or conditions of recording, and to
re-perform the authentication encoding process. Such a modified
digital recording would appear authentic.
[0020] The authentication decoding process analyses the digital
recording, the conditions of recording, and the authentication
record to determine if the digital recording and the conditions of
recording have been modified from the original.
[0021] A digital signature of the original recording data is
computed. The digital signature is a set of data containing fewer
bytes than the original recording data, but mathematically
representing the data content of the entire original recording. The
digital signature may be as simple as a checksum, or a more
complicated process containing many bytes. In a simple 8-bit
checksum, all of the bytes of the original recording are summed
(using 8-bit addition) while ignoring the carry resulting from the
addition. The 8-bit value representing the sum of all bytes in the
original recording is inverted (two's complement) and this 8-bit
value is the checksum. This provides a condition where the process
of summing all bytes of the original recording and then adding the
sum to the checksum will provide an overall sum of 0 if the
original data is unaltered. If any bits of the original data are
altered, this summing process will produce a non-zero sum, thus
indicating data corruption. However, an 8-bit checksum does not
provide strong capability to detect corruption. If many bits of the
original recording are randomly altered, the probability of a valid
8-bit checksum for random alterations is 1 in 256, or about 0.4%.
An authentication process would not be very strong if it failed to
detect corruption in 0.4% of the cases. To strengthen the
authentication process, many more than 8-bits will be used in the
digital signature data. In addition, the serial number of the
authentication encoder will be appended to the digital signature so
that an authentication decoder can determine which authentication
encoder created the authentication block which it is attempting to
verify.
[0022] The digital signature algorithm may be disclosed publicly,
or it may be kept as a trade secret by the provider of the
authentication process.
[0023] When the digital signature has been computed, it is
encrypted. The encryption process is as follows: The digital
signature `clear text` message. The encryption process translates
the `clear text` message into an encrypted message, a `cipher text`
message. A decryption process translates the `cipher text` message
back to the identical `clear text` message. This encryption process
can be performed with an encryption/decryption process that is
secret, or it can be performed with a disclosed algorithm that uses
either public keys or symmetric keys. This encryption process
prevents the generation of fraudulent authentication blocks.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 depicts the data flow through the authentication
encode process. The original digital recording 1 is combined with
the context 2 of the recording to compute a digital signature. The
context data 2 may include time, recorder number, information about
the operator, or other parameters. The digital recordings may be
prepared from sounds, pictures, temperature, location, or other
sensors. The digital signature of the original recording is
computed 3 using the encryption key 5. A process 4 is performed to
encrypt the digital signature. The original data recording 1, the
encrypted signature, and the context data 2 is then combined into
an authenticated recording 7 with a process 6. The authenticated
recording may be saved to digital recording media (memory or disk)
and it may be transmitted by local area network, internet, wired
telecommunications, or wireless telecommunications to other
processors or digital media. The authenticated recording may be
replayed by standard digital displays or players as if there were
no authentication block.
[0025] FIG. 2 depicts the data flow through the authentication
decode and verify process. The authenticated recording under test 8
represents the concatenation of the original recording 1, the
context data 2, and the encrypted digital signature. The
authentication block is separated in process 9 producing the
digital recording 10, the context data 11, and the encrypted
digital signature 12. A process 13 is performed to compute the
digital signature of the recording under test without the encrypted
digital signature 12 producing the computed digital signature. A
process 14 is performed to decrypt the digital signature of the
recording under test. The computed digital signature from process
13 is compared to the decrypted digital signature from process 14.
If these are identical, then the recording under test 8 is
authentic. If these are not identical, then the recording under
test is not authentic.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] The invention consists of an authentication encoder or an
authentication decoder or both an encoder and a decoder. The
authentication encoder is implemented in conjunction with a
recorder. The authentication encoder may be either tightly coupled
or loosely coupled with the digital recorder. If the authentication
encoder is integrated with the recorder and the authentication
encode process occurs at the same moment as the recording, then the
authentication encoder is tightly coupled with the digital
recorder. However, if the authentication encoder is separate from
the digital recording and the authentication encode process occurs
significantly later after the digital recording takes place, then
the authentication encoder is loosely coupled with the digital
recorder. The authentication encoder may be implemented as a
software process running on a general-purpose CPU, as a software
process running on a special-purpose CPU (such as a Digital Signal
Processor--DSP), or in hardware devices integrated with the
recorder hardware.
[0027] The authentication decoder is operated in conjunction with
devices that would permit review of the digital recording. In most
cases, the digital recording will be reviewed on a general-purpose
computer running review software. The authentication decoder will
most often be implemented as software running on a general-purpose
computer.
* * * * *